1. Technical Field
The present invention relates to a printed circuit board and a method of manufacturing a printed circuit board.
2. Description of the Related Art
The conventional multi-layer printed circuit board is manufactured by forming an inner layer circuit on the surface of a core substrate, such as of a copper clad laminate (CCL), by applying an additive process or subtractive process, and forming outer layer circuits by a method similar to that for the inner layer circuit while sequentially stacking insulation layers and metal layers.
With advances in electronic components, there is a growing demand for technology that can improve the performance of the HDI (high density interconnect) board, which employs interlayer electrical connection of circuit patterns and fine circuit wiring for a higher density printed circuit board. That is, to improve the performance of the HDI board, there is a need for enhanced technology in interlayer electrical connection for circuit patterns 20 and technology that provides freedom in design.
In manufacturing a multi-layer printed circuit board according to related art, half-etching is performed on a core substrate, such as that of a copper clad laminate (CCL), etc., to provide a thin thickness for the copper layer, and then after stacking a dry film, windows are opened by performing exposure, development, and etching at the positions where the BVH's (blind via holes) are to be formed. Then, the BVH's are processed by laser drilling, etc., and fill plating is performed to fill the BVH's and form a plating layer on the surface of the core substrate. Next, the surface of the core substrate is half-etched to make the thickness of the plating layer thinner, and a dry film is stacked again and exposure, development, and etching are performed to form circuit patterns. These processes are repeated to result in the manufacture of a multi-layer printed circuit board.
In other words, in manufacturing a multi-layer printed circuit board according to related art, either a copper clad laminate is used that has a thin copper layer of about 5 μm, or the copper layer of the copper clad laminate, which is the core substrate, is made thin by performing half-etching, and then the windows are opened, the BVH's are processed with laser, and half-etching is performed several times on the copper layer that has been made thicker by the fill plating, after which high-density inner layer circuits are formed, and these procedures are repeated to sequentially build up a multi-layer printed circuit board.
However, the conventional manufacturing process for a multi-layer printed circuit board, such as that described above, entails complicated processes and high manufacturing costs, due to the half-etching processes for decreasing the thickness of the copper layer or plating layer and plating processes for filling the BVH's. Also, forming the circuit patterns by repeatedly plating and etching imposes a limit to implementing high-density circuit patterns, and forming the circuit patterns by a series of stacking layers leads to long processing times.